回形针和嵌套表格，获取重复的条目

Question

我们正在尝试通过Paperclip gem将多个图片上传到我们的产品型号。问题是，每次我们提交表单时，已经附加到产品的每个现有图像都会再次添加，但没有任何属性。我们创建了以下嵌套表单：

<div class="product-form">
    <%= nested_form_for [:admin, @product], :html => { :multipart => true } do |f| %>
    <div>
        <%= f.label :category %><br>
        <%= f.select :category_id, Category.all.map{ |s| [s.name, s.id]}, :include_blank => true %>
    </div>
    <div>
        <%= f.label :name %><br>
        <%= f.text_field :name %><br>
    </div>
    <div>
        <%= f.label :price %><br>
        <%= f.number_field :price %><br>
    </div>
    <div>
        <%= f.label :discount %><br>
        <%= f.number_field :discount, :step => "any" %><br>
    </div>
    <div>
        <%= f.label :description %><br>
        <%= f.text_area :description %><br>
    </div>

    <table>
        <%= f.fields_for :stocks %> 
        <tr>
            <td><%= f.link_to_add "Add size", :stocks %></td>
        </tr>
    </table>
    <br>
    <table>
        <%= f.fields_for :images %>
        <tr>
            <td><%= f.link_to_add "Add image", :images %></td>
        </tr>       
    </table>
        <%= f.submit %>
    <% end %>

</div>

其中寻找以下部分：

<tr>
    <% if f.object.new_record? %>
        <td><%= f.file_field :image %></td>
    <% else  %>
      <td><%= f.object.image_file_name   %></td>
        <%= f.hidden_field :_destroy %>
        <td><%= f.link_to_remove "Remove" %></td>
    <% end %>
</tr>

图片模型

class Image < ActiveRecord::Base

    belongs_to :product

    has_attached_file :image, :styles => { :medium => "300x300", :thumb => "100x100" }, 
    :default_url => "/images/:style/missing.png"
  validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png"]

end

产品型号：

class Product < ActiveRecord::Base

    # Associations
    has_many :line_items
    has_many :carts, :through => :line_items
    has_many :stocks, :dependent => :destroy
    has_many :images, :dependent  => :destroy
    belongs_to :category
    accepts_nested_attributes_for :stocks, :images, :allow_destroy => true

    # Validations
    validates_presence_of :name, :price, :description, :category

    def create_stock(size, amount)
        Stock.create(size: size, amount: amount, product: self)
    end

    def self.categories     
        Product.pluck(:category).uniq
    end

    def sizes_in_stock
        stocks.where.not(amount: 0).map{ |s| s.size }
    end

    def price_after_discount
        has_discount? ? (self.price * self.discount/100).round(2) : price
    end

    def has_discount?
        !self.discount.nil?
    end

end

非常感谢任何帮助，谢谢